'After a failed attempt at racing a homemade billycart, Harriet's younger sister Kat becomes obsessed with speed. Kat is determined to take part in a billycart derby, but her parents will only allow Harriet to drive in it, as Kat is still too young. Harriet - pushed willy-nilly into the scheme - is terrified of getting behind the wheel again. On racing day, however, Harriet proves she's no chicken after all. She starts enjoying herself...until her crazy little sister manages to cause a big upset.' (Publication summary)
